Although the background of the invention is provided generally in the context of IEEE 802.16 networks, it should be understood that this is merely one example of a type of network with problems that can be addressed by the present invention. The Worldwide Interoperability for Microwave Access (WiMAX), based on IEEE 802.16 standard standards [1] [2], is designed to facilitate services with high transmission rates for data and multimedia applications in metropolitan areas. The physical (PHY) and medium access control (MAC) layers of WiMAX have been specified in the IEEE 802.16 standard. Many advanced communication technologies such as Orthogonal Frequency-Division Multiple Access (OFDMA) and multiple-input and multiple-output (MIMO) are embraced in the standards. Supported by these modern technologies, WiMAX is able to provide a large service coverage, high data rates and QoS guaranteed services. Because of these features, WiMAX is considered as a promising alternative for last mile broadband wireless access (BWA).
In order to provide QoS guaranteed services, the subscriber station (SS) is required to reserve the necessary bandwidth from the base station (BS) before any data transmissions. In order to serve variable bit rate (VBR) applications, the SS tends to keep the reserved bandwidth to maintain the QoS guaranteed services. Thus, the amount of reserved bandwidth transmitted data may be more than the amount of transmitted data and may not be fully utilized all the time. Although the amount of reserved bandwidth is adjustable via making bandwidth requests (BRs), the adjusted bandwidth is applied as early as to the next coming frame. The unused bandwidth in the current frame has no chance to be utilized. Moreover, it is very challenging to adjust the amount of reserved bandwidth precisely. The SS may be exposed to the risk of degrading the QoS requirements of applications due to the insufficient amount of reserved bandwidth.
Thus, despite the promise shown by WiMAX, problems remain with providing the desired QoS without overly decreasing bandwidth utilization. What is needed is improved protocols for implementation in network devices which overcomes these and other deficiencies.